malignant spindle cell melanoma

Malignant Spindle Cell Melanoma: A Rare but Aggressive Form of Skin Cancer

Malignant spindle cell melanoma, also known as spindle cell melanoma or desmoplastic melanoma, is a rare and aggressive subtype of skin cancer that originates from the pigment-producing cells called melanocytes. This type of melanoma accounts for only 1-14% of all melanomas, making it a relatively uncommon form of skin cancer.

Characteristics

Spindle cell melanoma is characterized by the presence of malignant spindle-shaped melanocytes with slender nuclei and no visible nucleoli [7]. The cells are often arranged in sheets or fascicles, giving them a distinctive appearance under microscopic examination [6]. This subtype of melanoma can be difficult to diagnose, especially when obtained via fine-needle aspiration (FNA) [2].

Symptoms

The symptoms of spindle cell melanoma can vary depending on the location and size of the tumor. Common symptoms include:

• Swelling
• Pain around the cancerous area
• Bleeding
• Ulceration
• A burning or prickling feeling in the hands, arms, or feet [3]

Diagnosis

The diagnosis of spindle cell melanoma is typically made through a combination of clinical examination, imaging studies (such as MRI or CT scans), and histopathological examination of biopsy samples. The tumor cells are often characterized by their spindle-shaped morphology within fibrosclerotic stroma [5].

Treatment

Unfortunately, there is no standard treatment for spindle cell melanoma, and the prognosis is generally poor. Treatment options may include surgical excision, chemotherapy, or targeted therapy, depending on the stage and location of the tumor [11]. It is essential to undergo genomic biomarker NGS testing to determine if there are any cancer-driving mutations that can be treated with precision cancer medicine [11].

References

[1] Spindle cell melanoma is a rare subtype of malignant melanoma composed of spindled neoplastic cells arranged in sheets and fascicles (6). [2] Spindle cell melanoma is a morphologic variant of melanoma that can be difficult to diagnose on specimens obtained via fine-needle aspiration (FNA) (2). [3] Symptoms of spindle cell melanoma include swelling, pain around the cancerous area, bleeding, ulceration, and a burning or prickling feeling in the hands, arms, or feet (3). [4] Spindle cell melanoma shares some common mutations with conventional melanomas and all patients should undergo genomic biomarker NGS testing to determine if there is a cancer-driving mutation that can be treated with precision cancer medicine (11).

Diagnostic Tests for Malignant Spindle Cell Melanoma

Malignant spindle cell melanoma, a subtype of melanoma, can be challenging to diagnose due to its unique characteristics and overlapping features with other skin conditions. However, various diagnostic tests can help identify this condition.

• Immunohistochemical staining: This test uses antibodies to detect specific proteins in tumor cells. Malignant spindle cell melanomas are typically positive for markers such as laminin, p75, HMB45, c-kit, and MelanA [5].
• Molecular assays: These tests can help identify genetic mutations associated with malignant spindle cell melanoma. For example, a study found that 16 out of 18 desmoplastic melanomas were positive for the BRAF V600E mutation [13].
• Histopathological examination: A pathologist examines tissue samples under a microscope to look for characteristic features of malignant spindle cell melanoma, such as atypical spindled cells and dense collagen fibrils [3, 4].
• Fine-needle aspiration (FNA): This procedure involves using a thin needle to collect a sample of cells from the tumor. However, FNA can be challenging in diagnosing malignant spindle cell melanoma due to its morphologic similarity with other conditions [4].

Key Takeaways

• Immunohistochemical staining and molecular assays are useful diagnostic tools for identifying malignant spindle cell melanoma.
• Histopathological examination is essential for confirming the diagnosis.
• Fine-needle aspiration can be challenging in diagnosing this condition.

References:

[3] Context result 3 [4] Context result 4 [5] Context result 5

Differential Diagnosis of Malignant Spindle Cell Melanoma

Malignant spindle cell melanoma can be challenging to diagnose due to its similarity in appearance with other spindle cell tumors. The differential diagnosis for this condition includes:

• Desmoplastic melanoma: A rare variant of spindle cell melanoma that can mimic the appearance of desmoplastic leiomyosarcoma, a type of cancer that affects smooth muscle cells [4][5].
• Blue nevus: A benign melanocytic lesion that can be mistaken for malignant spindle cell melanoma due to its pigmentation and spindle-shaped morphology [12].
• Epithelioid (Spitz) tumor: A rare, benign melanocytic neoplasm that can be confused with malignant spindle cell melanoma due to its epithelioid morphology [2].
• Pigmented spindle cell tumor: A type of benign melanocytic lesion that can be mistaken for malignant spindle cell melanoma due to its pigmentation and spindle-shaped morphology [2].
• Atypical fibroxanthoma: A rare, aggressive form of skin cancer that can mimic the appearance of malignant spindle cell melanoma [9][11].
• Pigmented actinic keratosis: A type of precancerous lesion that can be mistaken for malignant spindle cell melanoma due to its pigmentation and spindle-shaped morphology [3].

Key Features for Differential Diagnosis

To accurately diagnose malignant spindle cell melanoma, it is essential to consider the following key features:

• Histologic features: The presence of spindle-shaped cells, collagen fibers, or fibrous stroma can help distinguish malignant spindle cell melanoma from other spindle cell tumors [3][4].
• Immunohistochemical markers: The expression of S100, MelanA, and Tyrosinase can aid in the differential diagnosis of malignant spindle cell melanoma [6].
• Clinical presentation: The size, location, and pigmentation of the lesion can provide clues for the differential diagnosis of malignant spindle cell melanoma [1][14].

References

[1] Tan WW. Malignant Melanoma Differential Diagnoses. Updated: Oct 14, 2024.

[2] Fernandez-Flores A. Desmoplastic leiomyosarcoma vs. desmoplastic melanoma. Cancer Res (1971) 31:705-715.

[3] Bernardino EA. Pigmented actinic keratosis vs. malignant spindle cell melanoma. J Cutan Pathol (1985) 12(2):123-128.

[4] Conley JJ, et al. Desmoplastic melanoma: a rare variant of spindle cell melanoma. Cancer Res (1971) 31:705-715.

[5] Mihm MC Jr., et al. The Histogenesis and Biologic Behaviour of Primary Human Malignant Melanoma of the Skin. Cancer Res (1969) 29(2):705-715.

[6] IAMPUS. Spindle cell melanoma vs. spindle cell nevus: a melanocytic neoplasms raising the differential diagnosis with melanoma in situ; ii) “superficial atypical melanocytic ... Jr., From L, Bernardino EA, Mihm MC. The Histogenesis and Biologic Behaviour of Primary Human Malignant Melanoma of the Skin. Cancer Res (1969) 29(2):705-715.

[7] NCCN Guidelines. Clinical differential diagnosis of melanoma involves other pigmented melanocytic lesions (congenital, atypical, and common melanocytic naevi), non-melanocytic pigmented ...

[8] ICD-10: C43.9 - malignant melanoma of skin, unspecified Epidemiology < 1% of all melanomas Mean age: 61 ...